The Volt and the battery fires furor

17 November 2011

ON THE ROAD TO RALEIGH, N.C.–We're still rolling blissfully south toward our next big innovation stop here in Raleigh, and we've been catching up on news surrounding the Volt, its lithium ion (LiOn) battery and charging stations…specifically whether the Volt is a fire hazard.

Some sites have seized on the news to push LiOn technology as a killer in the wings; others offered a tempered view, suggesting that, at least for now, it's a tempest in a teapot.

To recap, we know of three fires in which Chevy Volts were involved or nearby:

1. A fire destroyed a garage in northwestern Connecticut. The owner–a volunteer firefighter named Storm–had a Volt and a home-converted Suzuku Samurai EV (pictured, right); here's his blog on the fire, where he writes "definitely not the Volt." (Here's local TV coverage.) No cause has been determined.

2. In Mooresville, N.C., a fire in a three-car garage that housed a Volt spread to and destroyed a luxury home. Initial suggestions identified the 240V charging station as the possible cause. That's been rejected since then, as fire officials have said the fire started away from the vehicles and charging station. But no cause has been determined.

3. The National Highway Transportation Safety Board crash-tested a Volt, pushing it into a pole at 20 miles an hour. The car performed well and was stored outside in the cold. Weeks later, the car caught fire. The fire apparently was caused by a short when the punctured coolant system leaked into the LiOn cells.

The LiOn challenge

We've known about LiOn benefits and hazards since the technology's introductions. Studies and observations have been unceasing. Last decade, the FAA looked into the matter after shipments of LiOn batteries caught fire aboard or near two planes.

Small fire sources can cause big problems, as LiOn cells quickly fuse together and propogate the fire. Some traditional suppressants like Halon 1301 (bromotrifluoromethane) might be ineffective; water is increasingly seen as the most effective way to put out such fires, according to a massive report put out this spring by the Fire Protection Research Council.

Last year, a cargo plane caught fire and crashed in Dubai carrying goods that included LiOn batteries. No cause has been identified.

Given the billions of LiOn batteries in the world, one could argue that failure incidents are marginal (how many lead-acid battery failures go unreported?).

But it's not a subject to be taken lightly. GM certainly isn't. It reported this week it's been sending SWAT-like teams to crash events to de-energize the batteries. GM EV global chief engineer Jim Federico stands by the company's EV innovation.

Given what you know, how would you design a LiOn-powered EV to be safer? Or is it safe enough?

 

Naomi November 21, 2011 at 5:08 pm

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Wonder how the safety of the LiOn batteries compares with that of gasoline in cars?

    Richie November 22, 2011 at 8:49 am

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    Don't know the answer for Gasoline VS LiOn but can tell you for years many in the hobby sectors useing rechargeable batteries have know and respected their dangers for causing fires. Fires can occur during discharge use and at the re-charging station. All these bateries (NiCad, N-MetalHidried,LiOn)  can become unstable. Therefore much more studies are needed with increased QA/QC. These car batteries hold a large capacity of engery just waiting to be released and when the fail they take the path of least resistance to discharge. What ever that is in their environment.
    Some well documented examples are failures in cell phones, laptop computers, and commercial hobby use.

    vandalii November 22, 2011 at 3:50 pm

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    The "explosive" car accidents seen on TV & in movies are mostly just that…on TV & in movies.
    Also keep in mind that 99.94% (approx ;-) ) of vehicles on the road are gasoline/diesel engines so when we hear about a fire related to one of the 21,000 or so Volts on the road vs. a fire related to the 100,000,000 or so petroleum-powered vehicles in the US, your PPM gets really skewed purely by population ;-)

Stephen Humphries November 21, 2011 at 8:42 pm

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Two risks in a crash.  Electricution, and Lithium Ion Battery Fires.  Internal force disconnect switches (multiple) within the battery pack should be a must.  Also, a sort of ion interupter chemical injected into each cell to render a normal battery chemical process useless, i.e. preventions of electricution, and fires.  This would be the equivalent of dumping baking soda in lead acid battery cells.  Lithium Ion batteries are real fire hazards, even in the small versions used for electric model RC aircraft.   I would never park a Lithium Ion Car in a building.   Charging these batteries is also very dangerous, as exceeding the battery voltage on a single cell can explode / ignite a fire.   Computers help, but are not fail proof.   For now, the best bet might be to "detach" the battery from the car in future designs for outside charging, and storage.  A very small golf cart type gasoline engine could power a small generator to move the car into the garage.   Lots of challenges.  I'm waiting for the simple gas saving ideas like auto engine start / stop at traffic lights.   How simple, and could save millions of gallons of gas every day in our busy cities.   Come on engineers.   And what about all those excess stop signs, and street lights that are not even timed with each other.  What a waste.  Let's get America moving again.  P.S.  Our Ford Commuter Van gets 150 miles to the gallon by having 10 people use the same vehicle for the daily grind to work.  The van itself 15 mpg.    Let's expand this idea to using electric cars at destination lots.  From there, people can take individual electric cars to their nearby work destinations.  If we can lick the fuel used to get to work, we all will enjoy the lower prices for our family vacations and personal road trips.   Keep up the good work! 

Robert Czarnek November 22, 2011 at 10:54 am

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Gasoline will burn only as fast as the oxygen supply allows. LiOn battery is more like an explosive. It contains lots of energy that can be released without external factors. I have seen a battery explode and disappear from my car. It was like a bomb. I have seen a battery cable melting on an exhaust pipe. It was like touching it with a welding electrode. Both gasoline and lithium are combustive. However, any battery technology brings a whole spectrum of other dangers into the game. I would not want it in my garage for at least ten more years if ever.
Volt is an expensive experiment with no economic justification. It is like a Prius with half a ton of batteries between the seats. Has lower highway economy at double the price. For that matter I make 36mpg in my Subaru Legacy with four wheel drive. That is almost Volts fuel economy in hybrid mode in highway driving. (official rating is 37mpg combined and 40mpg highway).
As long as we as a nation burn petroleum products in out electric plants electric vehicles border on lunacy. Only if we change to all nuclear or develop new and inexpensive methods of generating electricity the concept of electric vehicle might make some sense.

    Naomi December 2, 2011 at 3:48 pm

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    Some very interesting points from Robert — especially re the gas fire vs battery explosion. I agree that battery-powered cars are still in the infant stages, but I think the technology is worth pursuing. Battery size and efficiency improvements won't be made without some economic reason to fund the research.

    Cliff Taylor December 13, 2011 at 10:14 am

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    You are confusing Li-Ion and Li-Polymer batteries.  Li-Polymers can burn but not explode like the Li-Ion type since they don't hold pressure.  The Volt gets 40mpg on the highway after the battery goes dead but most people won't even use the ICE.  The Volt is the first step to getting out of oil dependence and onto many alternate energy solutions.  I think it's exciting to finally have an option not to use petroleum for transportation.  The battery pack weighs around 450 pounds, not half a ton.

Darwin Engwer December 14, 2011 at 4:18 pm

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The Chevy Volt battery pack has a total energy capacity of <a href="http://www.chevrolet.com/volt-electric-car/&quot; title="16 kWh">. A gallon of gasoline releases <a href="http://www.wolframalpha.com/input/?i=36.6+kwh&quot; title="36.6 kWh"> of energy upon combustion. Thus, a vehicle with nominally 10 gallons of gas on board carries 366 kWh of energy.
Safety is a somewhat elusive concept and takes many forms for both Li-ion batteries and gasoline. Gasoline safety includes mechanical enclosures (like the tank itself), placement of the tank, mounting of the tank, placement of the filler tube, the gas cap, routing and protection of the fuel line and fuel delivery subsystems (e.g. fuel injection or a carburetor).
Battery safety includes the mechanical enclosure (the battery "box"), cell-to-cell connections, routing of the battery cables as well as electronic monitoring, control, alert and active protection systems.
In a crash some or all of these safety components and mechanisms might be compromised. Thus resilience and fault tolerance become important factors.
Once a gasoline system has been breached a single spark unilaterally determines the outcome.
With a battery system, damage or failure of one or more cells can often be detected by a good battery monitoring/control/protection system i.e. the Battery Management System (BMS). The BMS is the most critical component in an EV, ensuring that the battery cells are balanced with respect to each other, monitoring for and actively preventing cell overcharging/overdischarging, and monitoring for unusual cell temperature and pressure changes. After a crash a good BMS may or may not be able to change the outcome, but at the very least it can alert the occupants or passersby of the state of the battery and the consequences of prolonged inaction (as in the NHTSB incident).

Darwin Engwer December 14, 2011 at 4:27 pm

Vote -1 Vote +1

[Reposting with improved text formatting.]
The Chevy Volt battery pack has a total energy capacity of 16 kWh.  A gallon of gasoline releases 36.6 kWh of energy upon combustion.  Thus, a vehicle with nominally 10 gallons of gas on board carries 366 kWh of energy.
 
Safety is a somewhat elusive concept and takes many forms for both Li-ion batteries and gasoline.  Gasoline safety includes mechanical enclosures (like the tank itself), placement of the tank, mounting of the tank, placement of the filler tube, the gas cap, routing and protection of the fuel line and fuel delivery subsystems (e.g. fuel injection or a carburetor).
 
Battery safety includes the mechanical enclosure (the battery "box"), cell-to-cell connections, routing of the battery cables as well as electronic monitoring, control, alert and active protection systems.
 
In a crash some or all of these safety components and mechanisms might be compromised.  Thus resilience and fault tolerance become important factors.
 
Once a gasoline system has been breached a single spark unilaterally determines the outcome.
 
With a battery system, damage or failure of one or more cells can often be detected by a good battery monitoring/control/protection system i.e. the Battery Management System (BMS).  The BMS is the most critical component in an EV, ensuring that the battery cells are balanced with respect to each other, monitoring for and actively preventing cell overcharging/overdischarging, and monitoring for unusual cell temperature and pressure changes.  After a crash a good BMS may or may not be able to change the outcome, but at the very least it can alert the occupants or passersby of the state of the battery and the consequences of prolonged inaction (as in the NHTSB incident).
 

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